Gene regulation in prokaryotes Flashcards
Does the larger the organism mean the larger the genome size?
yes
generally what has a larger genome, eukaryotes or prokaryotes?
eukaryotes
Is prokaryotic DNA exposed?
yes
Tell me about E. Coli’s genome, number of nucleotide pairs and how many proteins is approx. codes for?
- consists of a singular circular DNA molecule
- 4.6x106 nucleotide pairs
- encodes for approx. 43,000 proteins
generally, how many proteins do prokaryotic genomes encode?
1000-6000 proteins
Are prokaryotic genomes, diploid or haploid?
They only contain one copy of each gene
they are haploid
How is DNA stored in prokaryotes?
Whats an exception of this?
The DNA is compressed and packaged into a small space via supercoiling
The exception of a species within archaea which doesnt do this
Tell me about transcription and translation in prokaryotes?
The chromosomes are localised in the cytoplasm and transcription and translation takes place simultaneously
Whats a Nucleoside?
A nitrogenous base attached to a 5-carbon sugar

Whats a nucleotide?
A nucleoside attached to a phosphate group

How many H bonds between AT and CG?
CG has 3 H bonds
AT has 2 H bonds
What is a purine made from?
Purine = pyrimidine + imidazole
Whats an imidazole ?
A histamine side chain
Complete the label in the following structure


What are the purines and pyrimidines ?

Whats the structure of the purines and pyrimidines?


What are nucleoside analogues used for?
How are these components activated?
Why are they used?
nucleoside analogues are used as antiviral and anticancer agents
These components are activated in the cell by being converted to nucleotides
They are administered as nucleosides since charged nucleotides cannot easily cross cell membranes
Tell me the size of the following in DNA (in nm)…
- Diameter
- Major groove
- Minor groove
- Length of one turn
- DNA diameter= 2 nm
- Major groove in double strand is 2.2 nm = 22 Å
- Minor groove in double strand is 1.2 nm = 12 Å
- Length of one turn= 3.4 nm
What does the centra dogma of molecular biology deal with?
What does it state?
‘The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information’
It states that such information cannot be transferred back from protein to either protein or nucleic acid.’- Francis crick
Or more simply- DNA makes RNA and RNA makes protein

If you have more proteins at a higher level, do they make more or less mRNA?
They make more mRNA

What are the three common types of RNA and what is their role?
There are three common types of RNA:
1. mRNA or messenger RNA: This is the one that transcribes the genetic code from DNA into a form that is used to make protein. mRNA carries the message from the nucleus to the cytoplasm of the cell.
2. rRNA or ribosomal RNA: Forms structural elements of the ribosome that direct the translation of mRNA into protein.
3. tRNA or transfer RNA: tRNA transfers amino acids to the ribosome
is there a base 0 in DNA/RNA?
Which direction is upstream/ downstream?
no

if Uracil was present in DNA why would this cause issues?
If uracil was present in DNA then it would generate more errors due to the ability to bind with more
Which strand in DNA is copied?
What is T replaced with?
Why can T only pair with A?
What can U pair with why does this lead to less mutations?
It is the non-coding or template strand that is copied and thymine (T) is replaced with uracil (U)
Due to the methyl group, T can only base pair with A
while U can base pair with others – better DNA fidelity therefore less mutation




















